Solder preform loading method and apparatus

ABSTRACT

A method and apparatus for loading solder preforms on to the pins of a multiple pin connector. A positioning plate has open sockets in the pattern of the pins of the connector to be loaded, the sockets being sized to receive a single solder preform in each one. A slidable retainer fits into a channel below the positioning plate to partially close the sockets and retain preforms therein. Loose preforms are contained in a dam attached to the top of the positioning plate and are shaken into the sockets on a vibrator table. The dam and excess preforms are removed and the positioning plate is covered by a cover plate to hold the preforms in place. The connector pins are then inserted through slots in the retainer, through the preforms and through holes in the cover plate. The retainer is removed, allowing the preforms to drop on the pins and the loaded connector is removed from the apparatus.

This is a division of application Ser. No. 886,215 filed Mar. 13, 1978and now U.S. Pat. No. 4,164,064.

BACKGROUND OF THE INVENTION

In the assembly of multiple pin connectors to circuit boards and thelike, it is necessary to have each pin properly soldered to the circuitconnectors. To ensure uniformity in soldering it is a present practiceto apply a solder preform to each pin and melt all the preformssimultaneously by heating the pins. Each preform is a small cylindricalsection or toroid of solder material which must be placed over theindividual pin. Since some connectors have well over a hundred pins, itcan be a time consuming task to load the solder preforms. Tools andtechniques have been developed to handle the very small preforms, butthere is still a great deal of manual work and dexterity involved.

SUMMARY OF THE INVENTION

The apparatus described herein facilitates the loading of solderpreforms simultaneously on all the selected pins of a multiple pinconnector. A positioning plate has an array of open socketscorresponding to the arrangement of pins on the particular connectorblock to be loaded. A retainer slides into a channel in the underside ofthe positioning plate and partially blocks the sockets to hold solderpreforms in place, the retainer having slots through which the connectorpins can pass. Loose solder preforms are placed on the positioning plateand are confined by a dam attached to the positioning plate. Theassembly is shaken on a vibrator table so that the preforms drop intothe sockets. The dam and any excess preforms are them removed and acover plate is placed over the positioning plate to hold the preforms inthe sockets. The connector pins are inserted through the retainer andthe preforms and through pin holes in the cover plate, after which theretainer is slid out of the channel, allowing the preforms to drop tothe base of the connector pins. The connector is then removed with thepreforms loaded on all the selected pins.

The primary object of this invention, therefore, is to provide a new andimproved method and apparatus for loading solder preforms on the pins ofa multiple pin connector.

Another object of this invention is to provide solder preform loadingapparatus with means for holding preforms in a spaced array forsimultaneous placement on the pins of a connector.

A further object of this invention is to provide solder preforms loadingapparatus in which the preforms can be inserted in the holding means byvibration, requiring a minimum of time and manual dexterity.

Other objects and advantages will be apparent in the following detaileddescription in conjunction with the accompanying drawing, in which:

FIG. 1 is a perspective view of the separated components of theapparatus.

FIG. 2 is an enlarged side elevation view, partially cut away, of thepositioning plate and slide retainer.

FIG. 3 is a further enlarged sectional view taken on line 3--3 of FIG.2.

FIGS. 4 through 8 are sectional views similar to FIG. 3, illustratingthe steps in the method of loading the preforms on a connector.

FIG. 9 is an end elevation view of a typical connector with the preformsin place.

DESCRIPTION OF THE PREFERRED EMBODIMENT

The apparatus is very simple and comprises a positioning plate 10, witha slidably interfitting retainer 12, a cover plate 14, a dam plate 16,and a pair of alignment pins 18. In FIG. 1, the components areillustrated in their relative alignment, but it should be understoodthat the dam plate 16 and cover plate 14 are not actually used together.All of the plates are shown as simple rectangular members, but could beof any configuration as required. Each plate is provided with a pair oftooling holes 20 for receiving the alignment pins 18, which hold thedifferent plate combinations in alignment.

Positioning plate 10 has a channel 22 extending the full length thereofin the underside, the channel having dovetailed side walls 24 to holdthe similarly shaped retainer 12 in sliding relation. In the top surface26 of positioning plate 10 are sockets 28 arranged in a patterncorresponding to the layout of connector pins in the connector to beloaded. The sockets 28 extend through the positioning plate and openinto channel 22. For all standard connectors, the sockets will be inparallel rows longitudinal to the channel.

Retainer 12 has a plurality of longitudinally extending slots 30, openat one end, the slots being spaced to align with the rows of sockets 28.Each slot 30 is narrower in width than the diameter of the sockets 28,but wide enough for the connector pins to pass through.

Cover plate 14 has an array of pin holes 32 corresponding to and axiallyaligned with the sockets 28. Pin holes 32 are smaller than sockets 28and are sized to receive the connector pins.

Dam plate 16 has an opening forming a well 34, large enough to exposethe entire array of sockets 28 when the dam plate is attached topositioning plate 10, as in FIG. 3. In this initial assembly, held byalignment pins 18, loose solder preforms 36 are placed in the well 34,as indicated in FIG. 4.

Each solder preform 36 is a small cylindrical section or toroid ofsolder material of sufficient volume to form a good solder connection. Atypical preform is on the order of 0.058 inch outside diameter, with a0.03 diameter bore and is 0.03 thick, but the size can vary to suit thepin diameter and contact arrangement.

The assembly is placed on a vibrator table 38, or other vibratorysupport, which shakes the preforms 36 until they settle into sockets 28.Each socket is just large enough to hold a single preform in axialalignment, the preforms being held in the sockets by retainer 12.

The dam plate 16 is removed, leaving the positioning plate 10 loadedwith preforms 36, as in FIG. 5. To secure the preforms, the cover plate14 is placed over the top of positioning plate 10 and held by alignmentpins 18, as in FIG. 6, trapping the preforms in their sockets.

A connector 40 is then loaded by inserting its pins 42 through slots 30,through the preforms 36 and out through pin holes 32, as in FIG. 7. Theretainer 12 is then slid out, as in FIG. 8, allowing the preforms 36 todrop from the sockets 28 to the base of the respective pins 42.

Connector 40 is then removed from the apparatus with a solder preform 36on each pin 42, as indicated in FIG. 9. All the preforms are thus loadedsimultaneously without requiring any manual placement, which would bedifficult due to the small size of the preforms.

If certain of the pins 42 are not to be soldered, the respective sockets28 can be partially plugged to avoid receiving preforms. On thepositioning plate 10 can be initially set up by drilling smaller pinholes instead of sockets where the preforms are not required.

The apparatus facilitates the loading of preforms on very closely spacedpins. In some connectors, the pins in adjacent rows are staggered andthe rows are so close together that the preforms interfit with verysmall separation. The slotted retainer 12, which resembles a comb, willaccommodate very close row spacing, because the slots can be made withminimum separation. Since multiple pin connectors are normally made withthe pins arranged in rows for uniformity and convenience, the slidableretainer makes the apparatus adaptable to substantially all types ofmultiple pin connectors.

I claim:
 1. A method of loading solder preforms on the pins of amultiple pin connector, comprising:preparing a positioning plate havinga plurality of open sockets in a pattern corresponding to the pins ofthe connector to be loaded, attaching to the positioning plate aretainer which partially closes the sockets on one side, placing in eachsocket a substantially toroidal solder preform, inserting the pins ofthe connector through the retainer and through the solder preforms inthe sockets, removing the retainer, allowing the solder preforms to droponto the connector pins, and removing the positioning plate from theconnector.
 2. The method of claim 1, wherein the stop of placing thesolder preforms in the sockets includes attaching to the positioningplate a dam plate having a well which exposes the sockets, placing aplurality of loose solder preforms in the well, and vibrating the plateassembly to distribute the solder preforms in the sockets.
 3. The methodof claim 1 and including, after the step of placing the solder preformsin the sockets, the additional step of attaching to the positioningplate a cover plate having connector pin receiving holes in a patterncorresponding to the sockets, so that the solder preforms are enclosedin the sockets prior to insertion of the connector pins.